It is the news that no club manager wants to hear during the international break.
At the time of writing Arsenal boss Unai Emery still isn't fully aware of the severity of when playing for their countries over the weekend, with Xhaka himself claiming that his Achilles issue isn't too bad.
That won't comfort Emery until he can get club medical staff to take a look at the Switzerland captain though, and the same can be said for Torreira after he left Uruguay's friendly victory over Costa Rica before half-time on Saturday.
If both aren't available for Sunday's trip to Watford then Emery will be forced into at least two changes to his side, with the pair both starting the 2-2 draw with Tottenham over the international break.
One of those changes will surely be welcomed by plenty of Gunners fans though.
Dani Ceballos - who started Spain's 2-1 win over Romania last Thursday, before being an unused substitute in the 4-0 victory over the Faroe Islands on Sunday - could perhaps come back in to start, as many thought he should have done against Spurs.
The Real Madrid loanee impressed during his 76 minutes on the pitch in Bucharest, finding a teammate with 66 of his 69 passes.
That followed on from his impressive cameo in the North London derby , when Ceballos came on in the 63rd minute and helped Arsenal turn the screw in their eventually successful pursuit of an equaliser.
There's a real chance that the Spaniard would have started the game against the returning Quique Sanchez Flores' men anyway, and the other slot in midfield also looks to be fairly nailed on as well.
Joe Willock started the Gunners' first three Premier League games of the season before missing out against Spurs, and subsequently pulling out of the England under-21 squad as a precaution.
The youngster played in a slightly different position in the 3-1 loss at Liverpool when Emery interestingly opted to play a diamond formation, but usually he's been seen in central areas in all of his Gunners appearances.
Should he come into midfield then he'll likely be partnering the impressive Matteo Guendouzi, whose performances for his club this season earned him a spot in the senior France squad this week.
In terms of formation, Emery still needs to consider switching to a back three if he wants to get the best out of summer signing David Luiz, but with that hampering his chances of picking the front three that all Arsenal fans want to see, then he's likely to stick to four at the back.
That leaves Guendouzi and Willock charged with being the energetic forces in midfield, and Ceballos supporting the attack.
That could all end up looking like this:
Is this the side he'll go for in Hertfordshire?
Have your say in the comments below.
